Imperfections and small malfunctions in machines can sometimes cause contamination of the final products that roll off the production line. Metal particles can detach from the moving part of machines because of usage and friction and deposit on the product, sometimes compromising its quality irreversibly. This blog describes a technique that not only allows you to inspect for the presence of contamination, but also to identify its origination.

Search and destroy: product contamination

Whether it is to produce food, electronic devices or metallurgical components, the industrialization and automation of production processes has led to the introduction and implementation of sophisticated machines. These machines can have a short life-span or sometimes become defective after a certain amount of operational time, as the materials they are made from start to degrade, producing small particles as a result.

These particles can eventually deposit on products and contaminate food with potentially toxic metals. They could damage a detector or a printed circuit board (PCB), or even become the starting point for oxidation processes that will compromise the efficiency of mechanical components.

It is therefore crucial not just to detect such particles, but also to track their origin, so that operators on the production line can eliminate the issue. Several investigation options are available, depending on the nature and the size of the contaminating particles. Nevertheless, some techniques prove to be more efficient because they make full use of the chemical and physical properties of the materials being analyzed.

Electron microscopy for particle detection

The advent of electron microscopy for smaller industries, the huge improvement in the ease of use, the speed of the analysis, and the dramatic price drop, have revealed a whole new way of detecting contamination; one that is way more efficient and accurate than methods previously employed.

By using a SEM in combination with a backscattered electrons detector (BSD), it is possible to generate a high-magnification picture of the sample and particles, where different compositions are highlighted by different levels of contrast.

Figure 1: SEM image of a banana with metal particles contamination (brighter regions) and the surface of a PCB with dust (dark regions). The different composition is immediately visible, and specific analysis can be initiated in the suspicious areas.

Therefore, simply by scanning the surface of the samples, it is possible to detect all particles up to few tens of nanometers.

This process helps in identifying the existence of the contamination, but that is not the only information that a SEM can provide!

SEM and EDS: chemical composition analysis equipment

Electron microscopes can, in fact, be equipped with an energy dispersive X-ray detector (EDS or EDX). This means that within a few seconds, the same device can provide the accurate chemical composition of the sample being analyzed.

The results of this analysis can be further used to identify the source of the contamination (for example a very specific kind of steel or plastic used in a component of the production line) and selectively repair the machine responsible for the contamination. Within a few minutes, the quality of the product can be improved to the correct standard, and the production line optimized.

About the author

Luigi Raspolini is an Application Engineer at Thermo Fisher Scientific, the world leader in serving science. Luigi is constantly looking for new approaches to materials characterization, surface roughness measurements and composition analysis. He is passionate about improving user experiences and demonstrating the best way to image every kind of sample.